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HEART HEALTH

Exercise Boots Immunity

Exercise causes immune changes that may cut heart attack risk. Boston researchers found that a six-month exercise program, averaging 2.5 hours per week, improved immune function. Specifically, the exercise regimen led to a 36 percent increase in plaque-busting cytokine proteins, which are produced by mononuclear cells. At the same time, exercise led to a 58 percent reduction in different cytokines that could promote plaque formation.

Smith JK, Dykes R, Douglas JE, Krishnaswamy G, Berk S. Long-term exercise and atherogenic activity of blood mononuclear cells in persons at risk of developing ischemic heart disease. JAMA. 1999;281:1722-1727.

High Cholesterol and Violent Suicide

People with high cholesterol levels are more than twice as likely to commit violent suicide compared to those with lower cholesterol levels, according to Antti Tanskanen, M.D., and colleagues at Kuopio University Hospital in Finland. High cholesterol levels (in the 300 mg/dl range) were associated with a high frequency of suicide by hanging, firearms, cutting, or jumping. The findings were presented at the American Psychiatric Association annual meeting. Individuals on fatty, meaty diets tend to have higher levels of both cholesterol and testosterone (which is made from cholesterol), suggesting a possible explanation for aggressive behavior.

Butter or Margarine? Here's the Answer

Butter has been resoundingly condemned by cardiologists for its dangerous load of saturated fat, but stick margarines have hydrogenated oils that are loaded with trans fats that raise LDL (the "bad cholesterol") and lower HDL (the "good cholesterol"). So what should you spread on your toast? A Tufts University research team has the answer.

They put 36 men and women through a series of diets that were identical except for the type of fat used. Butter caused the highest cholesterol levels. And varying kinds of margarines and oil had these effects on cholesterol levels, compared to butter:

CHOLESTEROL 

Stick margarine -3%
Shortening -6%
Soft margarine -7%
Semiliquid margarine -10%
Soybean oil -10%

In each case, the total cholesterol: HDL ratio also dropped, except for stick margarine, which increased the ratio by 4 percent compared to butter. So the winners are semiliquid margarine and pure soybean oil. But the best answer of all is to buy a better brand of bread. It will taste good right out of the toaster without an added topping. Meats and dairy products also contain traces of trans fats, which are produced by bacterial fermentation in ruminant animals.

Lichtenstein AH, Ausman LM, Jalbert SM, Schaefer EJ. Effects of different forms of dietary hydrogenated fats on serum lipoprotein cholesterol levels. N Engl J Med. 1999;340:1933-1940.

EYE HEALTH

Macular Degeneration Linked to Heart Disease

Macular degeneration is a common cause of blindness in older persons. As Good Medicine has reported previously, high-fat diets increase risk of the disorder, and diets rich in green leafy vegetables reduce risk. These diet changes have a similar effect on heart disease, of course, a fact that was not lost on researchers writing in Ophthalmic Epidemiology. They looked for cardiac risk factors in people with macular degeneration and found them in spades: the same high-fat diets, smoking, hypertension, and diabetes that contribute to heart disease also increase risk of macular degeneration, suggesting that blood vessel damage may be the common thread.

Contact Lenses and Blindness

Extended-wear contact lenses may contribute to a rare but devastating infection of the cornea called microbial keratitis. The infection is caused by bacteria, fungi, amoebae, or viruses. Dutch researchers found that among wearers of rigid gas-permeable lenses, the risk of infection was 1.1 per 10,000 people. Risk was 3.3 times higher for those wearing soft lenses for 24 hours at a time or less, and nearly 20 times higher for those wearing soft lenses overnight.

Snow KK, Seddon JM. Do age-related macular degeneration and cardiovascular disease share common antecedents? Ophthalmic Epidemiol. 1999;6:125-143.
Cheng KH, Leung SL, Hoekman HW, et al. Incidence of contact-lens-associated microbial keratitis and its related morbidity. Lancet. 1999;354:181-185.

METABOLISM

Strengthen Bones with Fruit and Vegetables

Women with osteoporosis have had a variety of available treatments, notably the popular over-the-counter natural progesterone transdermal creams. While osteoporosis is less common in men, they have had fewer options when it does occur. A new study shows that men can take a precautionary step by emphasizing fruits and vegetables in their diets. Tufts University researchers found that men who eat the most fruits and vegetables have denser bones than other men. The researchers gave the credit to the potassium and magnesium in plant foods. Plants are also low in sodium and omit animal proteins, both of which are well known to encourage calcium loss.

Tucker KL, Hannan MT, Chen H, Cupples LA, Wilson PW, Kiel DP. Potassium, magnesium, and fruit and vegetable intakes are associated with greater mineral density in elderly men and women. Am J Clin Nutr. 1999;69:727-736.

Improving Insulin Sensitivity

A low-fat diet helps insulin work better, although the diet's power may depend on genetic factors, according to a study from Louisiana State University. Insulin is a hormone that pushes sugar and protein from the bloodstream into the cells of the body. When people eat fatty foods or gain weight, insulin works less effectively. Jennifer Lovejoy and her colleagues found that a diet reducing fat intake to 20 percent of energy increased insulin sensitivity by 6 percent in a group of African-American women and 20 percent in Caucasian women. Lower-fat, vegetarian diets and added exercise cause an even greater effect.

Lovejoy JC, Windhauser MM, Rood JC, de la Bretonne JA. Effect of a controlled high-fat versus low-fat diet on insulin sensitivity and leptin levels in African-American and Caucasian women. Metab. 1998;47:1520-1524.

CROSS-SPECIES TRANSPLANTS

New Doubts about Xenotransplants

Efforts to place animal organs in humans (xenotransplants) have been dealt severe blows recently:

First, a study by S.J. Crick and colleagues at the Imperial College School of Medicine reported that a pig heart's shape, blood vessel connections, and other anatomical features render it a far less than perfect substitute for a human heart.

Then, the Council of Europe put a moratorium on clinical tests of animal organ transplants into humans, due to concerns that pigs harbor viruses that may pose serious health threats to humans, as well as concerns about the welfare of the animals. The Council did not stop animal-to-animal transplant experiments, but the decision put a major damper on efforts to make the transplants feasible.

The shortage of transplantable organs has been used as a rationale for the growing number of commercial xenotransplant speculators, but better methods of access to transplantable human organs, coupled with preventive measures designed to reduce the need for transplants, could close the gap much more easily. PCRM has issued detailed comments against cross-species transplants to the Food and Drug Administration.

A recent article in Science downplayed the danger of viruses in pig organs, reporting that one virus, porcine endogenous retrovirus (PERV), had not yet surfaced in individuals treated with experimental pig cell or organ transplants. However, other viruses continue to present threats. The Menangle virus first emerged in a group of pigs in Sydney Australia in 1997 and proved capable of causing birth defects. Pigs from this group had been used in an experimental xenotransplant program but were not screened for the virus because it was unknown at the time. The researchers later decided to withdraw from the xenotransplant program.

On September 30, 1999, Pittsburgh researchers revealed that a baboon liver had transmitted cytomegalovirus to a human recipient in a 1992 experiment.

Crick SJ, Sheppard MN, Ho SY, Gebstein L, Anderson RH. Anatomy of the pig heart: comparisons with normal human cardiac structure. J Anatomy. 1998;193(pt.1):105-119.
Paradis K, Langford G, Long Z, et al. Search for cross-species transmission of porcine endogenous retrovirus in patients treated with living pig tissue. Science. 1999;285:1236-1240.

MED-CETERA

Herbal Tea and Tropical Fruit Linked to Parkinsonism

The French West Indies have a high prevalence of atypical parkinsonism and progressive supranuclear palsy (PSP), diseases that are similar to Parkinson's disease. Dr. Dominique Caparros-Lefebvre found that, compared to patients with classic Parkinson's disease, those with atypical parkinsonism or PSP had consumed more herbal tea and fruits of the Annonaceae (custard apple or pawpaw) family, which contain neurotoxic alkaloids.

Caparros-Lefebvre D, Elbaz A, and the Caribbean Parkinsonism Study Group. Possible relation of atypical parkinsonism in the French West Indies with consumption of tropical plants: a case-control study. Lancet. 1999;354:281-286.



 

Autumn 1999 (Volume VIII, Number 4)

Autumn 1999
Volume VIII
Number 4

Good Medicine
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